In a semiconductor integrated circuit, elements (for example, transistors) that make up logic circuits and arithmetic circuits and the interconnects for connecting these elements are formed on a semiconductor substrate.
In a programmable semiconductor integrated circuit such as an FPGA (Field Programmable Gate Array), the wiring or the logic can be altered after having assembled the semiconductor integrated circuit. In a programmable semiconductor integrated circuit, the operation information and connection information of logic circuits and arithmetic circuits are stored in memory elements, and the wiring or logic is altered based on the stored operation information and connection information. Elements such as SRAM cells and floating-gate MOS transistors are known as this type of memory element. Fuses or anti-fuses are also known as switching elements for altering wiring connections. However, fuses or anti-fuses are not capable of multiple alterations of wiring.
Patent Document 1 (JP-A-2005-101535) discloses a semiconductor integrated circuit having electrolytic switching elements that are capable of multiple alterations of wiring by using oxidation-reduction reactions of the electrolyte. In this electrolytic switching element, a first electrode is formed of a metal that is difficult to ionize, such as platinum, and a second electrode is formed of a metal that is easy to ionize, such as copper. In addition, a solid electrolyte such as copper oxide is interposed between the electrodes.
When voltage is applied to the first electrode that is lower than voltage applied to the second electrode, electrons from the second electrode are supplied to the electrolyte, and a metal dendrite (metal precipitate) is deposited on the first electrode.
When the application of voltage is then continued, the metal dendrite deposited at the first electrode gradually becomes larger and contacts the second electrode. In other words, the first electrode and the second electrode are connected by way of a metal dendrite. In this way, an electrical connection is established between the first electrode and the second electrode.
When voltage is applied to the first electrode that is greater than the voltage to the second electrode when the first electrode and second electrode are in a connected state, electrons are released from the metal dendrite that connected the first electrode and second electrode and the metal dendrite becomes smaller. When the application of voltage is then continued, the first electrode and second electrode are disconnected. The first electrode and second electrode are thus isolated.
In this electrolytic switching element, the conductive state and isolated state can be altered a plurality of times by altering the direction of the voltage applied across the electrodes.    Patent Document 1: JP-A-2005-101535